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FreeBSD-SA-09:15.ssl                                        Security Advisory
                                                          The FreeBSD Project

Topic:          SSL protocol flaw

Category:       contrib
Module:         openssl
Announced:      2009-12-03
Credits:        Marsh Ray, Steve Dispensa
Affects:        All supported versions of FreeBSD.
Corrected:      2009-12-03 09:18:40 UTC (RELENG_8, 8.0-STABLE)
                2009-12-03 09:18:40 UTC (RELENG_8_0, 8.0-RELEASE-p1)
                2009-12-03 09:18:40 UTC (RELENG_7, 7.2-STABLE)
                2009-12-03 09:18:40 UTC (RELENG_7_2, 7.2-RELEASE-p5)
                2009-12-03 09:18:40 UTC (RELENG_7_1, 7.1-RELEASE-p9)
                2009-12-03 09:18:40 UTC (RELENG_6, 6.4-STABLE)
                2009-12-03 09:18:40 UTC (RELENG_6_4, 6.4-RELEASE-p8)
                2009-12-03 09:18:40 UTC (RELENG_6_3, 6.3-RELEASE-p14)
CVE Name:       CVE-2009-3555

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.

0.   Revision History

v1.0 2009-12-03  Initial release.
v1.1 2009-12-03  Corrected instructions in section V.2)b).

I.   Background

The SSL (Secure Sockets Layer) and TLS (Transport Layer Security) protocols
provide a secure communications layer over which other protocols can be
utilized.  The most widespread use of SSL/TLS is to add security to the
HTTP protocol, thus producing HTTPS.

FreeBSD includes software from the OpenSSL Project which implements SSL
and TLS.

II.  Problem Description

The SSL version 3 and TLS protocols support session renegotiation without
cryptographically tying the new session parameters to the old parameters.

III. Impact

An attacker who can intercept a TCP connection being used for SSL or TLS
can cause the initial session negotiation to take the place of a session
renegotiation.  This can be exploited in several ways, including:
 * Causing a server to interpret incoming messages as having been sent
under the auspices of a client SSL key when in fact they were not;
 * Causing a client request to be appended to an attacker-supplied
request, potentially revealing to the attacker the contents of the client
request (including any authentication parameters); and
 * Causing a client to receive a response to an attacker-supplied request
instead of a response to the request sent by the client.

IV.  Workaround

No workaround is available.

V.   Solution

NOTE WELL: This update causes OpenSSL to reject any attempt to renegotiate
SSL / TLS session parameters.  As a result, connections in which the other
party attempts to renegotiate session parameters will break.  In practice,
however, session renegotiation is a rarely-used feature, so disabling this
functionality is unlikely to cause problems for most systems.

Perform one of the following:

1) Upgrade your vulnerable system to 6-STABLE, 7-STABLE, or 8-STABLE, or to
the RELENG_8_0, RELENG_7_2, RELENG_7_1, RELENG_6_4, or RELENG_6_3 security
branch dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 6.3, 6.4,
7.1, 7.2, and 8.0 systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch http://security.FreeBSD.org/patches/SA-09:15/ssl.patch
# fetch http://security.FreeBSD.org/patches/SA-09:15/ssl.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/secure/lib/libssl
# make obj && make depend && make includes && make && make install

NOTE: On the amd64 platform, the above procedure will not update the
lib32 (i386 compatibility) libraries.  On amd64 systems where the i386
compatibility libraries are used, the operating system should instead
be recompiled as described in
<URL:http://www.FreeBSD.org/handbook/makeworld.html>

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

CVS:

Branch                                                           Revision
  Path
- -------------------------------------------------------------------------
RELENG_6
  src/crypto/openssl/ssl/s3_pkt.c                            1.1.1.10.2.1
  src/crypto/openssl/ssl/s3_srvr.c                           1.1.1.14.2.3
  src/crypto/openssl/ssl/s3_lib.c                            1.1.1.10.2.1
RELENG_6_4
  src/UPDATING                                            1.416.2.40.2.12
  src/sys/conf/newvers.sh                                  1.69.2.18.2.14
  src/crypto/openssl/ssl/s3_pkt.c                           1.1.1.10.12.1
  src/crypto/openssl/ssl/s3_srvr.c                       1.1.1.14.2.1.6.2
  src/crypto/openssl/ssl/s3_lib.c                           1.1.1.10.12.1
RELENG_6_3
  src/UPDATING                                            1.416.2.37.2.19
  src/sys/conf/newvers.sh                                  1.69.2.15.2.18
  src/crypto/openssl/ssl/s3_pkt.c                           1.1.1.10.10.1
  src/crypto/openssl/ssl/s3_srvr.c                       1.1.1.14.2.1.4.2
  src/crypto/openssl/ssl/s3_lib.c                           1.1.1.10.10.1
RELENG_7
  src/crypto/openssl/ssl/s3_pkt.c                            1.1.1.12.2.1
  src/crypto/openssl/ssl/s3_srvr.c                           1.1.1.17.2.2
  src/crypto/openssl/ssl/s3_lib.c                            1.1.1.13.2.1
RELENG_7_2
  src/UPDATING                                             1.507.2.23.2.8
  src/sys/conf/newvers.sh                                   1.72.2.11.2.9
  src/crypto/openssl/ssl/s3_pkt.c                            1.1.1.12.8.1
  src/crypto/openssl/ssl/s3_srvr.c                       1.1.1.17.2.1.2.1
  src/crypto/openssl/ssl/s3_lib.c                            1.1.1.13.8.1
RELENG_7_1
  src/UPDATING                                            1.507.2.13.2.12
  src/sys/conf/newvers.sh                                   1.72.2.9.2.13
  src/crypto/openssl/ssl/s3_pkt.c                            1.1.1.12.6.1
  src/crypto/openssl/ssl/s3_srvr.c                           1.1.1.17.6.2
  src/crypto/openssl/ssl/s3_lib.c                            1.1.1.13.6.1
RELENG_8
  src/crypto/openssl/ssl/s3_pkt.c                                 1.2.2.1
  src/crypto/openssl/ssl/s3_srvr.c                                1.3.2.1
  src/crypto/openssl/ssl/s3_lib.c                                 1.2.2.1
RELENG_8_0
  src/UPDATING                                              1.632.2.7.2.4
  src/sys/conf/newvers.sh                                    1.83.2.6.2.4
  src/crypto/openssl/ssl/s3_pkt.c                                 1.2.4.1
  src/crypto/openssl/ssl/s3_srvr.c                                1.3.4.1
  src/crypto/openssl/ssl/s3_lib.c                                 1.2.4.1
- -------------------------------------------------------------------------

Subversion:

Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/6/                                                         r200054
releng/6.4/                                                       r200054
releng/6.3/                                                       r200054
stable/7/                                                         r200054
releng/7.2/                                                       r200054
releng/7.1/                                                       r200054
- -------------------------------------------------------------------------

VII. References

http://extendedsubset.com/Renegotiating_TLS.pdf

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-3555

The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-09:15.ssl.asc
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